Bijdragen lot de Dierkunde, 59 (4) 243-249 (1989) SPB Academie Publishing bv, The Hague A tantulocaridan Dicrotrichura tricincta gen. et spec. nov.: new (Crustacea: Maxillopoda) from the Mediterranean deep waters off Corsica Rony Huys MarineBiology Section, Zoology Institute, State University of Gent, K.L. Ledeganckstraat 35, B-9000 Gent, Netherlands Belgium and Delta Institutefor Hydrobiological Research, Vierstraat 28, 4401EA Yerseke, The water Keywords: Tantulocarida, Dicrotrichura tricincta gen. et sp. nov., Mediterranean, deep Summary small-sized maxillopodan genera Basipodella Beck- er and Deoterthron Bradford& Hewitt, the number The new genus and species, Dicrotrichura tricincta, is described of divided in nine species has raised to 17, at present from deep mud (1220 m) in the Ligurian Sea (western Mediterra- and five families Lincoln genera (Boxshall & 1987; nean). It is the first tantulocaridan not found to be attached to Huys in press). All tantulocaridanshitherto known a crustacean host but free living in the sediment. It is assigned are of other crustaceans. to the Deoterthridae on the basis of the absence of a rostrum, obligate ectoparasites the abdominal segmentationand the characteristic cephalic pore Most species show a high level of host specificity pattern. It can be distinguished from all known tantulocaridans and utilize harpacticoids, tanaids or isopods as in the presence of peculiar, bi-articulated caudal setae and the hosts although a few species are known to parasitize difference in thoracopodal setation between leg 2 and legs 3-5. ostracods and cumaceans. Boxshall & Lincoln Some new structures located on the attachment disc are an excellent of the described for the first time. D. tricincta is the second tan- (1987) provide analysis highly abbreviated life which tulocaridan to be recorded from the Mediterranean. cycle includes an infective tantuluslarva, a swollen sac-like female and a free- swimming male. Starobogatov's (1986) untenable Résumé to the Tantulocarida proposal group (as a super- Dicrotrichura tricincta n. n. le second Tantulocaride g., sp. est order Basipodelliformii) together with the gymno- connu provenant de la Méditerranée. Il provient de la vase plean copepods in the infraclass Calanioini was re- profonde (1220 m) de la Mer Ligurienne (Méditerranéeocciden- jected by Grygier & Sieg (1988) and Boxshall & tale). D. tricincta est le premier tantulocaride vivant libre dans Huys (1989). The latter authors, inspired by the ho- le sédiment, et non attaché à un Crustacé hôte. L’absence d’un of the male tantulocaridan rostre, la segmentationabdominale et le patron caractéristique mology penis, suggested des céphaliques le classent dans la famille des Deoterthri- instead pores that their relationships may lie with the D. dae. tricincta se distingue de tous les Tantulocarides connus 'thecostracan group' of Maxillopoda which in- la de soies caudales bi-articulées différence par présence et par la cludes also the Ostracoda, Branchiura and Theco- entre la position et le nombre des soies sur les thoracopodes 2 et straca Une (sensu Grygier, 1987). 3 à 5. description est donnée de structures nouvelles sur le Tantulocaridans disque d’attachement. are very uncommon in the Med- iterranean but this should primarily be attributed to the low levpl of sampling effort in this area, Introduction rather than to any defined zoogeographical pat- Since Boxshall & Lincoln (1983) formally estab- terns. The only mediterraneanfind thus far, consti- lished the class Tantulocaridato accommodate the tutes in fact the first record of a tantulocaridan, * Contribution No. 452 of the Delta Institute for Hydrobiological Research, Yerseke. 244 R. Huys - Mediterranean deepwater Tantulocaridan such. abdomen. however, without having been recognized as pedigerous somites, and a 2-segmented In 1903 Bonnier described Cumoniscus kruppi on First thoracic tergite largely concealed beneath of dorsal shield. the basis of a single specimen, obviously a female, posterior margin cephalic Cephalic of ornamentation of 4 and referred the species to an unnamed family shield triangular; consisting an- at surface lamel- epicaridean isopods. It was collected by dredging terior plus 6 posterior pairs of pores, C. lae absent. curved in lateral 1000 m depth near the Isle of Capri, Italy. krup- Cephalic stylet slightly found of view. 1 5 each pi was attached to an undescribed species Thoracopods to with unsegmented Leuconidae and represents thus far the only pub- protopod bearing a well developed medial endite. lished account of a cumacean-infesting tan- Exopod of thoracopods 1 to 5 apparently 1-seg- unable tulocarid. Boxshall & Lincoln(1987) were to mentedwith 2 (leg 1), 3 (leg 2), or 4 setae (legs 3-5). place the species in any of the existing families be- Endopod 1-segmented with 0 (leg 1) or 2 setae (legs cause of lack of detailed information (Bonnier did 2-5). Thoracopod 6 without distinct rami, with not give any illustrations) and because both the coupling spines on medial margin of protopod and male and the tantulus are unknown. Hence, they 2 setae apically. Second abdominal somite with 3 sedis the somite. ranked Bonnier's species as incertae within transverse lamellae running around the class and regarded the sac-like habitus and the an- Caudal rami distinct, armed with 1 short and 2 teriorly located, minute adhesive disc as sufficient long, bi-articulate setae. Host unknown. evidence to keep C. kruppi in the Tantulocarida. Most recently Boxshall (pers. comm.) found a sec- Etymology. - The generic name is derived from the ond cumacean-parasitizing tantulocaridan, proba- Greek dikroös, meaning forked, trichos, meaning from in tail bly belonging to Cumoniscus, deep water hair, and oura, meaning and refers to the the Gulf of Biscay. peculiarly shaped, caudal setae. Gender: feminine. tantulus from 1220 A single was caught m depth in theLigurian Sea (western Mediterranean), repre- Type and only species. - Dicrotrichura tricincta Deoterthridae senting a new genus and species of spec. nov. described below. It is the first record of a tantulus attached but stage not found to a crustacean host, living free in the sediment. Description Dicrotrichura tricincta spec. nov. (figs. 1A-B; Methods 2A-E) The holotype tantulus was examined as a temporary preparation Tantulus larva in glycerin. All drawings were made under oil immersion using a Leitz Dialux 20 microscope with interference contrast. Judi- Body (figs. 1A-B) comprising a cephalon covered cious manipulationof the coverslip allowed careful examination free and by a dorsal shield, 6 thoracic somites, a of the detailed morphology of the thoracopods and the cepha- 2-segmented abdomen. Totalbody length about 83 lon. After completing the description, the specimen was trans- ferred to lactophenol mounting medium and the preparation /jm, measured from the tip of the cephalon to the BDH was sealed with glyceel (Gurr®, Chemicals Ltd, Poole, posterior margin of the abdomen. Cephalon trian- England). gular, tapering anteriorly towards the oral disc; posterior margin straight with posterolateral angles Taxonomy represented by slightly pronounced lobes; ventro- lateral margins with incision. Cephalic shield about Dicrotrichura gen. nov. 1.14 times longer than wide (32 /xm X 28 ¿im); two dorsal, longitudinal surface lamellae extend to the Diagnosis. — Class Tantulocarida. Family Deoter- basis of the oral disc. The rostrum is absent. The thridae. 6 oral disc is in diameterand is Tantulus larva comprising cephalon, about 8.5 /¿m posi- Bijdragen tot de Dierkunde 59 (4) - 1989 245 Dicrotrichura tricincta view Fig. I. gen. et sp. n. A, holotype tantulus, dorsal view; B, same, lateral (thoracopodal setae omitted). - 246 R. Huys Mediterranean deepwater Tantulocaridan tioned far anteriorly so that it is visible in dorsal dite proximally, two spiny processes along the outer the disc the dorsal distal aspect; is invaginated at midline, margin and two spinous processes at the outer filament-like the lateral margins each have 3 struc- corner. Under light microscope a subapical spine tures, the ventral margin forms a lobe-like exten- and a blunt process are visible on the edite. Rami sion which is basally directed. A peculiar funnel- one-segmented. Exopod short, with two strong and middorsal inci- shaped organ is discernible near the one (leg 2) or two (legs 3-5) slender naked setae. sion of the oral disc; this slender, hollow structure Endopod one-segmented, long, with swollen basal minute and further and thin-walled distal armed has a pore apically seems to run part a tapering part; towards muscle-like strand which is with two setae with internally a outer-margin laterally; apex in comparable both in appearance and position two processes, the outer one being spatulate. with the striated organ mentionedin earlier descrip- Sixth thoracopod (fig. 2D) with simple protopod tions. Internal structures other than the cephalic lacking medial endite, but bearing two coupling stylet were too small for them to be described ade- spines on the medial margin; outer margin with 3 quately. There are 10 pairs of simple pores on the spinous processes. Rami not distinct but possibly sides shield; 4 pairs in the anterior part (on both ar- represented each by a vestige bearing a strong ranged in the typical deoterthrid L-pattern) and 6 naked seta. of which is in pairs around the posterior margin 1 pair The abdomen(figs. 1 A—B; 2E) 15 /¿m length is located subdorsally and another one surrounds a and two-segmented. The first abdominal somite is of the covered 2.9 times wider than 3 the tiny sensillum; some pores were by long (8.7 /¿m x /¿m), small bulb-shaped bodies of hyaline substance. The second 1.2 times longer than wide (12 /¿m x 10 ventral surface of the shield lacks pores and lamel- /xm). First somite without surface ornamentation. lae altogether. There are no cephalic appendages. Second somite tapering anteriorly; ornamented is about and with lamellae The cephalic stylet 22 /¿m long slight- 3 ring-shaped transverse giving the curved both in dorsal and in lateral view. The somite Ventral ly tip a 4-segmented appearance.